The present invention relates to a link mechanism for a vehicular cruise control apparatus which is usable with a left-sided steering-wheel car or a right-sided steering-wheel car.
FIGS. 3 and 4 show a known link mechanism for a vehicular cruise control apparatus. The known link mechanism illustrated includes a first lever 1, a second lever 2 and a third lever 3, all of which are of semicircular configurations and rotatably mounted on a support shaft 4 in such a manner that they are rotatable relative to the support shaft independently of each other. A main frame 5 has a pair of upright brackets 50, 51 on which the support shaft 4 is fixedly supported at the opposite ends thereof.
The first lever 1 comprises a pair of opposed sector-shaped side plates 10, 11 which are integrally secured to each other at their central boss portions to form a kind of a semicircular pulley. The plate 10 has one end thereof outwardly bent at right angles to form an engagement piece 1a. The other plate 11 has one end thereof opposing to the other end of the plate 10 outwardly bent at right angles to form an engagement piece 1p. The thus constructed first lever 1 is urged by a coiled spring 100 in such a manner that the engagement piece 1a thereof is placed into abutting engagement with a corresponding engagement piece 5a of the upright bracket 50. In FIG. 3, the engagement piece 1a of the plate 10 abuts against the engagement piece 5a of the upright bracket 50 from the right-hand direction. A first or accelerator cable 6 extending from an unillustrated accelerator pedal of the vehicle upwardly extends around the semicircular circumferential periphery of the first lever 1 so as to be connected at one end thereof with a T-shaped attachment 1n of the first lever 1. Thus, when the driver steps on the unillustrated accelerator pedal, the first lever 1 is caused to rotate around the support shaft 4 against the bias of the coiled spring 100 through the pull of the accelerator cable 6 in proportion with the extent to which the accelerator pedal is depressed. Specifically, the engagement piece 1a of the plate 10 is moved to the right in FIG. 3 in a direction away from the engagement piece 5a of the upright bracket 50. When the accelerator pedal is released, the first lever 1 is caused to return to the illustrated initial position under the action of the coiled spring 100.
Likewise, the second lever 2 comprises a pair of sector-shaped side plates 20, 21 which, like the first lever 1, are integrally secured to each other at their central boss portions to form a kind of a semicircular pulley. The side plate 20 has one end thereof outwardly bent at right angles to form an engagment piece 2p which is placed in confrontation with the engagement piece 1p of the first lever 1. As shown in FIG. 3, the engagement piece 2p of the plate 20 is located above the engagement piece 1p of the first lever 1 in confrontation therewith. Accordingly, as the first lever 1 rotates against the bias of the coiled spring 100, the second lever 2 is caused to rotate through the engagement of the engagement piece 2p thereof with the engagement piece 1p of the first lever 1. However, when the second lever 2 follows the motion of the third lever 3, which will be described later in detail, the engagement piece 2p of the second lever 2 moves in a direction away from the engagement piece 1p of the first plate 1. The side plate 20 also has the other end inwardly bent to form an engagement piece 2t. A second or throttle cable 7 extending from an unillustrated throttle valve to the second lever 2 downwardly extends around the semicircular-shaped circumferential periphery of the second lever 2 from the top to the bottom thereof so as to be connected at one end thereof with a T-shaped attachment 2n of the second lever 2 in the same manner as with the first lever 1 at a location near the engagement piece 2t. Thus, as the driver steps on the accelerator pedal, the accelerator cable 6 is pulled by the accelerator pedal so as to rotate the first lever 1 through an angle proportional to the extent to which the accelerator pedal is depressed. In accordance with the rotation of the first lever 1, the engagement piece 1p thereof upwardly pushes the engagement piece 2p of the second lever 2, thereby causing the second lever 2 to rotate around the support shaft 4 in a direction to move the unillustrated throttle valve in the opening direction through the throttle cable 7. On the other hand, when the accelerator pedal is released, the first and second levers 1 and 2 are restored to their initial positions as illustrated in FIGS. 3 and 4 under the action of the coiled spring 100 and an unillustrated return spring which acts to urge the throttle valve in the closing direction.
The third lever 3 comprises a pair of opposed sectorshaped side plates 30, 31, as in the case of the first and second levers 1, 2. The side plate 30 is integrally formed at one end thereof with an engagement piece 3t at a location confronting the engagement piece 2t of the second lever 2. As shown in FIG. 3, the engagement piece 2t is located below the engagement piece 3t in a confronting relation therewith. Likewise, the other side plate 31 is integrally formed, at one end thereof opposing the other end of the side plate 30, with an engagement edge 3b which is disposed in confrontation with an engagement piece 5b which is integrally formed with, and inwardly bent substantially at right angles from, the upright bracket 51 of the main frame 5. The third lever 3 is urged by a coiled spring 300 in such a manner that the engagement edge 3b thereof is placed in abutting engagement with the engagement piece 5b of the upright bracket 51. Specifically, as shown in FIG. 3, the engagement edge 3b abuts against the engagement piece 5b from the left. This biasing direction of the engagement edge 3b due to the coiled spring 300 is the same as that of the first lever 1 due to the coiled spring 100. A third or actuator cable 8 extends from an unillustrated cruise control actuator to the third lever 3 from a direction opposite to the direction from which the accelerator and throttle cables 6 and 7 extend to the first and second levers 1, 2. The actuator cable 8 downwardly extends around the semicircular-shaped circumferential periphery of the third lever 3 from the top to the bottom thereof. In this manner, the actuator cable 8 is connected at one end thereof with a T-shaped attachment 3n of the third lever 3 in the same manner as with the accelerator cable 6. Thus, as the unillustrated cruise control actuator is energized, the third lever 3 is caused by the actuator to rotate around the support shaft 4 against the bias of the coiled spring 300. In accordance with the rotation of the third lever 3, the engagement piece 3t thereof pushes down the engagement piece 2t of the second lever 2 so as to rotate the second lever 2 in such a direction as to move the engagement piece 2p thereof away from the engagement piece 1p of the first lever 1, thereby causing the unillustrated throttle valve to open. When the actuator is deenergized, the second and third levers 2, 3 are restored to their initial positions as illustrated in FIGS. 3 and 4 under the action of the coiled spring 300 and the unillustrated return spring which urges the throttle valve in the closing direction.
The operation of the above-mentioned known link mechanism will now be described in detail. First, let us consider the case in which the vehicle performs normal travel without cruise control. In this case, when the driver operates to change an unillustrated transmission so as to select an appropriate gear ratio and then steps on the accelerator pedal in order to accelerate the vehicle, the first lever 1 is first caused to rotate through the pull of the accelerator cable 6 whereby the second lever 2 is rotated through the engagement between the engagement pieces 1p, 2p. Accordingly, the second lever 2 operates to pull the throttle cable 7, thus moving the throttle valve in the opening direction. As a result, large amount of air/fuel mixture is sucked into the engine of the vehicle so as to increase the rotational speed of the engine, thus accelerating the vehicle.
Subsequently, when the driver starts cruise control after the speed of the vehicle reaches a certain level, the unillustrated cruise control actuator is energized by an output signal from an unillustrated speed sensor to provide a pull on the actuator cable 8, thereby rotating the third lever 3. At this time, even though the driver still continues to step on the accelerator pedal, the engagement piece 3t of the third lever 3 remains out of engagement with the engagement piece 2t of the second lever 2 since the second lever 2 follows the motion of the first lever 1. However, the engagement piece 3t of the third lever 3 comes into the vicinity of the engagement piece 2t of the second lever 2, so that when the driver releases the accelerator pedal, the second lever 2 is forced to return to its initial position due to an unillustrated return spring which urges the throttle valve in the closing direction. Accordingly, the engagement piece 2t of the second lever 2 is placed into abutting engagement with the engagement piece 3t of the third lever 3 so that the second lever 2 is forced to follow the motion of the third lever 3, thus making the vehicle travel under the control of the cruise control actuator.
In addition, during the time that the vehicle is travelling under cruise control, when the driver steps on the brake pedal or releases the cruise control, the cruise control actuator is deenergized to return to the initial condition, placing the vehicle under normal control in which the driver can normally control the vehicle through the accelerator pedal.
Although there are two kinds of automobiles, i.e., one having a right-hand steering wheel and the other having a left-hand steering wheel, the positions of a throttle valve and a cruise control actuator are the same or constant irrespective of these kinds of automobiles, but the position of an accelerator pedal alone varies, i.e., it is located on the right side or the left side in a driver's compartment of a vehicle, depending upon the kinds of automobile. As a result, the above-described known link mechanism having one and the same construction can not be equally applied to a right-hand steering-wheel automobile and a left-hand steering-wheel automobile. The link mechanism shown in FIG. 3 is for a left-hand steering-wheel automobile and hence the accelerator cable 6 extends from the first lever 1 towards an unillustrated left-hand accelerator pedal. In order to apply the illustrated link mechanism to a right-hand steering-wheel automobile, it is necessary to reverse the right and left portions thereof, but in this case, the throttle cable 7 is disposed on the right side and the actuator cable 8 is disposed on the left side. Therefore, in the past, two kinds of link mechanisms had to be manufactured, one for a right-hand steering-wheel automobile and the other for a left-hand steering-wheel automobile. As a result, the production costs as well as storage costs for producing and storing in warehouses two kinds of link mechanisms become relatively high as compared with those for a single kind of link mechanism.